Fluid flotation separator and method for separating pulverized materials



Sept. 21, 1954 A. E. DILLIARD FLUID FLQTATION SEPARATOR AND METHOD FOR SEPARATING PULVERIZED MATERIALS Filed Aug. 9, 1951 :5 sheets-sheet 1 fillen/ E105 Ilia/rd 5'ua m p 21, 1954 A. E. DILLIARD 2,689,646

FLUID FLOTATION SEPARATOR AND METHOD FOR SEPARATING PULVERIZED MATERIALS 3 Shee'ts-Sheet 2 Filed Aug. 9, 1951 filler lfflilh'wrd as, Qlula M Sept. 21, 1954 A. E. DILLIARD 2,689,646

FLUID FLOTATION SEPARATOR AND METHOD F OR SEPARATING PULVERIZED MATERIALS 3 Sheets-Sheet 3 Filed Aug. 9, 1951 awe/11M flllemilflilliwrd Patented Sept. 2 1, 1954 FLUID FL'OTATION 'SEPARATOR AND METH- OD FOR S'EPABATING PULV-ERIZED MA:

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Allen E. Billiard, Woodley Hills, Va. Application Augustfl, 1951, *Serial No. 241,080

21 Claims.

This invention relates to a method and apparatus for separating or classifying pulverized materials and more particularly to a method and apparatus for ,fiuid flotation separation.

The principles of gas and liquid flotation have been employed in many methods and separators for the purpose of separating and classifying granular or pulverized materials. In many instances such methods and separators have unsatisfactory due to low efiiciency which nocessitates recycling the pulverized material through the separator a large number of times. This inefficiency is due, in part, to the difficulty in dislodging and rendering buoyant an effective quantity of the fine particles of material distributed throughout the body of the pulverized material subjected to flotation. Furthermore, in the separation of finely pulverized materials by gas flotation methods the material becomes fluidized and there is then "a tendency for the fines to agglomerate and form heavy nodules. The particles of which a nodule com-posed are mutually attracted by forces so great that the nodules are not broken down by the flotation gas. The weight {of these nodules is such that they are not rendered buoyant by the flotation gas which results in all of the fine particles of material contained the nodules remaining in the pulverized material.

The foregoing objections are overcome by this invention which, briefly, comprises conveying a pulverized material over an inclined porous surface at an appreciable speed by passing a stream of gas under pressure through the porous surface from below and thence through the pulverized material. As the pulverized material is thus conveyed in a stream over the porous surface, small port-ions of the moving material are agitated to break down the nodules. Simultaneously small portions of the material adjacent the upper surface of the material stream-are elevat-ed above the stream and thereafter permitted to fall in a cascading effect through-the flotation gas flowing upwardly from the surface of the material stream. The fine particles of material in the cascading portion are rendered buoyant and become entrained in the flotation gas. The agitation and elevation of the pulverized mate.- rial :is produced by a plurality of deflector members disposed above the porous partition at an angle thereto. The angle between the face of each deflector adjacent the uppermost end of the porous partition and the surface of the par.- tition extending from the lower end of the dc.- doctor to the uppermost end :of the porous :par-

tition is an obtuse angle. These deflectors each comprise, preferably, "a relatively narrow :elons gated member aor group :of members formed from any material capable of providing either a rigid or slightly resilient member. Each deflector is ity of the flotation gas as it iilows upwardly from the surface of the material stream; and, after the flotation gas the fine particles of ma.- terial entrained therein have been conducted to a collector, to reduce the velocity of the flotation gas to permit the .fine particles of material to settle from the flotation It is, therefore, the principal object of this invention to provide a separator and 133 method for separating pulverized materials wherein the material is conveyed over an inclined porous surface -:at :an appreciable speed by passing a stream of gas under pressure through theporous surface from below; and, while the material is thus being conveyed, small portions of the ma: terial moving only relatively close to the upper surface of the material stream are agitated without materially reducing the speed of the material stream and elevated above the :s'urlfia'ce of the material stream, after which such po-rtions are released and permitted to fall in the path of the upwardly flowing stream of fi'o'tat'ion gas.

Another important object of this invention is to provide a separator comprising a porous surface over which a pulverized material may be conveyed by the action of a gas under pressure flowing upwardly through the porous suit-ace, and a plurality of pulverized material agitating and elevating deflector members disposed at {all angle above the porous surface and spaced thereabove a distance such that the terminal end of each deflector extends below the surface of the conveyed pulverized material to a point relatively close to the surface of the material.

It is also an object of this invention to provide a separator .wherein the degree of fineness of the separator product obtained may Jae controlled by adjusting the rate of new of the gas passing through the porous surface with a single gas flow control means. 1

sesame Another object of this invention is to provide a means for increasing the velocity of a stream of flotation gas flowing upwardly from the surface of a stream of pulverized material as the latter is conveyed over an inclined porous surface by the action of the gas stream passing through the porous surface from below and through the pulverized material.

Still another object of this invention is to provide a means for reducing the velocity of a stream of flotation gas having fine particles of material entrained therein as the stream passes through a collector to permit the fine particles of material to settle from the flotation gas rapidly.

A further object of this invention is to provide a separator chute having a transverse partition of porous material set at an angle to the horizontal and adapted to pass gas under pressure and support a pulverized material, and a plurality of relatively narrow elongated deflector elements positioned above the partition at an angle thereto for agitating and elevating small portions of material adjacent the upper surface only of the pulverized material supported on the porous surface.

A still further object of this invention is to provide a separator chute of the foregoing type having side walls inclined towards each other adjacent the upper edges thereof, one of the side walls having an outlet port formed therein and positioned at a location where the maximum velocity of the flotation gas containing entrained fines occurs.

Other and more specific objects will be apparent from the following description taken in conjunction with the accompanying drawings, wherein:

Figure 1 is an overall schematic view in section on line |-l of Figure 2;

Figure 2 is a top plan view;

Figure 3 is a side elevational view of the separator casing;

Figure 4 is a sectional view on line 4-4 of Figure 6;

Figure -5 is a sectional view showing the inlet end of a material chute;

Figure 6 is a sectional view showing the discharge end of a material chute;

Figure "7 is a fragmentary sectional view of a material chute showing a modified form of material elevating member;

Figure 7a is a view on line la-4a of Figure 7;

Figure 8 is a fragmentary sectional view of a material chute showing another modified form of a material elevating member:

Figure 8a is a view on line 8u-8a of Figure 8;

Figure 9 is a fragmentary sectional view of a material chute showing still another modified form of a material elevating member;

Figure 9a is a view on line Bot-9a of Figure 9;

Figure 10 is a side elevational view of a modified form of a separator with portions thereof removed;

Figure 11 is a sectional Figure 10;

Figure 12 is a sectional view of another modified form of a separator; and

Figure 13 is a sectional view of a simplified form of a separator.

Referring to Figures 1, 2 and 3, a' fluid flotation separator embodying the principles of this invention is shown. The separator includes a vertically extending rectangular casing it! having a gas outlet 1 l at the top of the casing. The outview on line H-ll of 4 let I I may comprise a frame member 12 supported above an opening l3 in the top H! of the casing by vertical members l5 which are attached to the top of the casing adjacent the opening therein. The opening in the frame member l2 and the spaces between the frame and the top Is are covered with a filter fabric l6 through which gas may pass but through which fine particles of material are not permitted to pass. A collec tor bin I! having the shape of an inverted trapezoid is attached to the lower end of the rectangular casing ID; The base of the trapezoid collector bin attached to the casing has the same dimensions as the casing. The bottom of the collector bin l! is provided with .an outlet !8 having a valve I9 to permit periodic withdrawal of the finely divided pulverized material which collects in the separator. One or more bafiles 20 are mounted inside the casing It. Each baffle 20 is positioned adjacent a wall of the casing it and extends downwardly from the top is to a point just below the connection between the collector bin l1 and the casing and may be support ed by one or more struts 2|. baffle is approximately coextensive with the width of the adjacent wall of the casing H3. The baffle 2|! diverges outwardly. from the adjacent wall of the casing [0 toward the vertical axes at the center of the casing. The face of a baffle and the casing wall opposedthereto, or the opposed faces of two or more baflles 20 cooperate to form a vertical converging gas return or exhaust stack leading to the gas outlet. Each wall of the easing [0 adjacent a baflie 20 is provided with a plurality of narrow elongated slots 22 which provide inlet openings. The inlets 22 are each inclined with respect to the horizontal and are arranged vertically in zig-zag relation.

A plurality of relatively narrow elongated separator chambers '23 are secured to the outer face of a side wall of the casing It, each chamber being positioned so as to cover an inlet opening 22 in the side wall of the casing. The separator chambers 23 are positioned at approximately the same angle of inclination with respect to the horizontal as that of the corresponding slot forming the inlet opening 22. The separator chambers 23 are, therefore, arranged serially in zig-zag relation in vertical tiers on a side wall of the casing l0 and each chamber is co-extensive with and covers the adjacent inlet opening 22. The separator chambers 23 are provided with a porous partition 24 which is inclined at an angle to the horizontal corresponding, approximately, to the angle of inclination of the chamber Within which it is supported. The porous partitions 24 are formed of a material which will permit gas under pressure to pass therethrough and which will also support a pulverized material. The outer side wall 25 of the separator chamber located above the porous partition 24 is preferably inclined toward the side wall of the vertically extending casing Ill. The portion of the side wall of the casing lo that is opposed to the side wall 25 of the chamber may be inclined toward the side wall 25. However, as will be shown in the discussion of Figures 4., 5 and 6 below, in order to simplify the installation of the separating chambers 23, it is preferred to form an elongated opening in the casing In which is deeper than that shown in Figure 1. Thus, it is preferred to make the depth of such an opening equal to about the height of a chamber from the point at which the partition is located to the top of the chamber.

The width of the The chamber 23 which is then at-.

it angle with respect to thehorizontal.

tached to the casing N! 'to cover the opening formed therein is provided with an inner side wall having a narrow elongated slot formed therein adiacent the top thereof and the inner side wall is inclined toward the wall '25. The bottom of each separator chamber 2 3 located below the porous partition 24 is provided with a plenum chamber 25 which is shallow adjacent the ends of the separator chamber and gradually increases in depth from each end thereof to a point located at about the middle'of the lengthwise dimension of the plenum chamber '26. "The plenum chamber 26 has :a generally pyramidal shape and the outer side wall of each such chamber is provided with an opening 2 adapted to receive a branch line 28 of manifolds it through which gas under pressure is supplied by the blower 29 to theplenum chamber 26. l

The upper end of each separator chamber 23 is provided with an inlet opening in order that pulverized material may be fed to the raised end of the porous partition'24. The lower end of each separator chamber 23 is provided with an outlet for pulverized-material which has'been conveyedover the porous partition 24. The inlet of the separator chamber 23 at the top of the vertical tier of chambers is provided with a hopper 3t anda gate 3! which permits pulverized material to be fed to the raised end of the porous partition 24 but prevents-gas fiowing in the chamher to pass out of the inlet end thereof. The outlet of each of the separating chambers 23 is connected to the inlet end of the next lower chamber by a connector spout 3'2. The outlet end of the lowermost separating chamber 23 has a discharge spout '33 connected thereto and an outlet gate 34 is provided at the point of attachment between thespout 33 and the chamber 23 to permit the withdrawal of the pulverized material which has passed through the flotation separatorbut which prevents the loss of gas flowing in the lowermost separating chamber. In each separating chamber 23 "there are positioned a plurality of pulverized material agitating and elevating deflectors 35 which are inclined at an Thus-each deflector 35 within a chamber 23 is inclined towardthe outlet end of the ch'amber and the lowermost edge of each deflector extends toward the inlet end :of th'echamber. The deflectors 35, whihmayassume .a variety of forms and shapes as will be shown hereinafter, are mounted in the separating chambers 23 with the lowermost or leading edges thereof spa'c'ed above the porous partition 24. The deflectors 35 are thus arranged so that the lower edges thereof extend below the surface of the pulverized material to a point "relatively close to the upper surface or stratum of the stream of pulverized material conveyed upon the porous partition 24. The speed with which the material 'is conveyed over the porous partition is, therefore, not materially reduced.

Referring to Figures 4, and 6 the preferred structure of the separating chambers is shown in enlarged fragmentary views with a pulverized material passing therethrough over the porous partition. The preferred manner of attaching a separator chamber 23 to the outer side wall of the casing I l! is-shown in Figure 4. Thus, in lieu of form-ing an inclined slot to provide an inlet opening 2 2 and inclining the portion of the side wall of the easing I I) outwardly toward the oppo'sedside wa1125 of "the separating chamber as described above, a large inclin'ed opening 336 :is

formed in the side wall of the casing 1 0. separating chamber .23 which "is attached to the side wall of the casing l'l! includes an outer :side wall 25 which is bent over to provide a top 31 for the chamber. The top 13*! "is provided with a flanged portion 38 provided with openings which are aligned with corresponding openings in the side wall of the casing it, the aligned openings being adapted to receive bolts 39 :or

edge of the side wall =40 is provided with a lhorizontally extending portion 443 :and .a downwardly extending flanged portion '44. The flanged portion 44 is attached to the side wall of the casing m below the edge of the opening :35 by means f bolts 45 which extend through openings provided in the side wall of thecasing and the flange 44. The outer side wall :25 is provided with a flanged portion 45 which extends outwardly and is aligned with the horizontal portion 43 of the inner side Wall 40 of the separating chamber. The side edges of the plenum chamber '26 are provided with horizontally extending portions ll- 41 which may be aligned with the flange 3 86 on the outer side wall '25 and the horizontal portion :43 of the inner side wall '40 land the side edges of the porous partition :21 are clamped between these several ali'gned portions. These aligned portions are provided with openings adapted to receive bolts which secure the plenum chamber 26 and the porous partition :21 to the side walls 25 and 49 of the separating chamber.

The inner-side wall lm-of the separatingchamber is provided with an inclined inarr'ow elongated slot which provides an inlet opening 222 leading into the casing ill. The iporous partition 2:; may be formed of any material which will support :a pulverized material and which also will permit gas under pressure to :pass therethrough. closely woven fabric may be used as we'll porous ceramic-slabs; such as, for example ip'or'ous silica or slatebase slabs employed insewage disposal plants as filter blocks. Untreated cotton transmission belting has been'employed-efiectively in the separator chambers of this invention.

The inlet end of the separatingchamber adjacent the top of the vertically extending-casing i0 is shown in Figure 5. Thehopper =30 includes downwardly extending side walls '49 and 50, the latter of which is provided with a flanged portion '51 provided with openings. The end of the plenum chamber 26 is provided with offset horizontal portion 52 having openings formed therein. This ofise't portion functions as a support for the end edge of the porous partition 24 which may be secured thereto by rivets 53 or like securing means. The offset portion 52 terminates in a downwardly-extending flange 54 which rests against the flanged portion 5' I of the hopper 30. The hopper may be secured tothe plenumchamber 26 bybolts 55 which extend through openings provided in the flanged portions 5| and -54. "The end gate 34 :is :supported between the wall 49 of the hopper $0 and theinlet end of the separator chamber and is .sliclably mounted therein to control :the irate 7 of flow of pulverized material from the hopper 30 to the raised end of the porous partition 24, while preventing gas from escaping from the chamber.

The outlet end of the lowermost separating chamber 23 in the vertical tier thereof is provided with a discharge spout 33 having a flanged portion 56 at the lower edge thereof adjacent the end of the plenum chamber 26. The latter is provided with an offset horizontal portion 53 for supporting the end edge of the porous partition 24 as described above in connection with the inlet end of the chamber. A corresponding flanged portion 54 may be secured to the flange 56 of the discharge spout 33 by bolts which extend through openings provided in the flanges 54 and 56. A gate 34 is slidably mounted between the outlet end of the separating chamber and the adjacent discharge spout to control the flow of pulverized material from the separating chamber without permitting loss of gas flowing in the chamber 23. It will be understood that the gates 3| and 34 as well as the hopper 3!! may be replaced with other equipment commonly employed for the purpose of introducing pulverized material into, or withdrawing such material from, a chamber without permitting loss of a gas flowing in such chamber. Among other expedients employed for this purpose are star type rotary feeders or a screw conveyor made to run with a full trough of material.

The pulverized material agitating and elevating deflectors 35 shown in Figures 4, 5 and 6 consist of straight or planar sections of a reticulated material; such as for example, wire screening. These deflectors are secured to the side walls 25 and 40 of the separating chamber 23 in any desired manner; such as, for example, by soldering or welding. It is essential to employ a screening, the mesh of which is large enough to permit the pulverized material being conveyed over the porous partition 24 to flow through separating chamber without materially reducing the speed of the flowing stream of material. A screening having openings in the mesh thereof has been found to be satisfactory for many uses. The appropriate size employed, however, depends upon the materialbemg treated and the condition thereof e. g. moisture content, and changes may be made according to specific requirements. The deflectors 35 are arranged at spaced intervals in the separating chamber 23 above the porous partition 24. The deflectors are inclined toward the outlet or lowermost end of the chamber and are spaced above the porous partition 24 so that the lowermost edges of the deflectors extend into only the upper surface or stratum of the material flowing over the partition. The deflectors 35 agitate the pulverized material flowing adjacent the lowermost ends thereof to break up the nodules formed therein and release the finely divided particles of which the nodules are composed. Simultaneously, the deflectors 35 elevate small portions of the material from only the upper surface of the stream of material flowing over the porous partition 24, above the upper surface of this stream. The portions elevated are composed of both coarse and fine particles which, after being elevated, are released and permitted to fall with a cascading action into 'the stream of flotation gas flowing upwardly through the separation chamber 23 from the upper surface of the stream of moving material. The coarser particles fall through the upwardly flowing gas back into the stream of flowing material along with some of the finer particles of material and are again conveyed over the porous partition to the next deflector. A high proportion of the fine particles of material falling in the upwardly flowing gas are rendered buoyant by the flotation gas; and, upon becoming entrained in the gas are conveyed from the separating chamber through the inlet 22 into casing It). This agitating and cascading effect is shown in Figures 4, 5 and 6.

The pulverized material agitating and elevating deflectors may be constructed in a variety of modified forms which are shown in Figures '7 to 9a. In Figures '7 and 7a the deflectors 35 depicted consists of an arcuate reticulated member. The deflector shown in this modification is formed from the same type of material and is mounted in the same manner as the deflectors shown in Figures 4, 5 and 6. The modified deflector shown in Figures '7 and '70; differs from those shown in Figures 4, 5 and 6 only in that it is arcuate in shape whereas the deflectors of Figures 4, 5 and 6 are straight or planar in shape. Another modified form of deflector shown in Figures 8 and 8a consists of triangular plates 58 attached to the side walls 25 and 40 of the separating chamber 23. These plates are arranged in staggered relation on opposite sides of the chamber and are inclined toward the outlet of the separating chamber 23. Each triangular plate 58 is also curved so that the apex of the triangle projecting toward the center of the chamber 23 is bent forwardly and extends toward the inlet end of the chamber 23. Therefore, the face of each triangular plate 58 nearest the inlet end of the separating chamber is gradually concavely curved from the side wall of the chamber toward the center thereof. The lowermost edge of the form of deflectors shown in Figures 8 and 8a are spaced above the porous partition 24 so that this edge extends only a relatively smal distance into the surface of the flowing stream of material. In order to obtain the desired agitation of the surface of the flowing material and to elevate small portions of material adjacent the surface of the material it is essential that the deflectors 58 do not extend outwardly from the side wall of the chamber more than approximately one third the total width of the stream of material conveyed over the porous partition 24. Still another modified form of deflector is shown in Figures 9 and 9a. The deflector, in this modification, consists of a plurality of spaced narrow elongated strips 59, formed from metal or other relatively rigid material. The strips 59 are secured to a supporting cross-member 60 which is attached to the inner face of the side walls 25 and 40 of the separating chamber 23. The strips 59 may be flat as shown in Figure 9a or arcuate as shown as 5911 in this figure, in dotted lines.

In the operation of the fluid flotation separator shown in Figures 1 to 6 the principles of the Polysius conveyor for pulverized materials are employed. This type of conveyor utilizes a porous support for the pulverized material which is inclined at an angle to the horizontal that is greater than the aerated angle of repose of the pulverized material. When air under pressure is passed through the porous support and the pulverized material, from below, the latter attempts to assume, but never achieves, its aerated angle of repose. As a result thereof, the entire mass will flow over the porous support toward the lowermost end thereof. The rate of flow may be controlled bycontrolling the. amount. of gas passing through the. material and by varying the angle of inclination of the porous support. If the minimum angle of inclination of the porous. support is once determined fora particular type of'material in a specific condition, the rate of flow of the material may be controlled by controlling the flow of gas through the material. In conveyors of this type the material may beconveyed at velocities ranging from about 50 feed/min. to well above 200 feet/min. It is essential to convey the pulverized material over the porous partition 21 in the separator chambers 23 in the fluid flotation separators of: this invention at a high velocity.

An important feature. of this invention consists in deflecting a portion. of the particles of. pulverized material to. a position above the upper surface of the stream or material conveyed over the porous partition 24 in the separator chamber 23. While the particles are suspended above the main material stream. it'is easier for the gas to carry off the fines as there would be less particle collision than if the fines had to be blown up through a stream of material that, is only fluidized. The flotation separators employed heretofore make use of a stratification. of material according to particle size, the smaller particles being on top and the particle sizes becoming progressively larger towards. the bottom.

This stratification is caused by fluidization. of the material. In order to cause such stratification by fluidization a prolonged time is required; and, after a very short period of fluidization of the material, it has been noticed that small nodules of material form which crumble when an attempt is made to pick them up. These are, however, suflicie-ntly solid to hold together while the gas passes around them without breaking upthe nodules. The nodules are formed before. any definite stratification of particle sizes is noticed. The nodules withhold particles of... a size that would or could be cariecl off if they were not retained in the nodule. It has been noticed that these nodules were formed bycement upon which classification tests were com ducted and it is known that this agglomeration will occur in other pulverized materials. that have-the characteristics of cement; such as lime, flour, c-lays, cryolite and the like; The high stream velocity dashing the material and nodules against the deflectors is sufllcient to break up the nodules and the particles retained; therein receive the same treatment as the unagglomerated particles. l

The gas is forced by a fan orpositive displacement blower 29 throng-ha control valve 29a to a manifold that feedstheplenum chambers 26 where the gas passes through; the porouspartition 24 and then through the pulverized ma-- terial.

The control valve 29a. permits the. operator to adjust the flow of gas to. the plenum chamber to control the velocity or the pulverized material flowing over the. porous. partition; and, at. the. same. time, to control the rate of flow of flotation gas in the separating chamber above, the surface of the moving stream of pulverized material. A sin l control is thus provided whereby, for a particular pulverized material in a known condition, the rate of flow of gas. to the. plenum chambers may be varied to obtain the desired separator products. After the gas. passes through the pulverized material the velocity is increased due to. the decrease in. the cross sectional shape as it approaches the collecting chamber [1.

From the bottom of the settling chamber the. gas passes over the collecting chamber l1 and 'then upward through the diverging space between the.- opposed baflies 20 and to the atmosphere or a dust collector, it necessary.

Pulverized material from the hopper is fed into the separator chamber through: the airlock or adjustable gate 31. The material flows through the chambers 23 above the porous partition 24' at a velocity of about 200; feet per min. As the pulveri'zed material flows through the chamber the material flows against deflectors 35- which deflect a portion of the material stream to a posh tion above the main stream. Only a. portion of the material stream is deflected so as: to main tain. the stream velocity. At the point of deflection, the separation of the fines from the coarse material takes place. The coarse material reenters the main pulverized material stream and the stream moves on to the next deflector to be deflected again in part. The. main material stream finally passes from the separator through the adjustable gate 34-.

The fine particles are entrained and carried off by the gas stream into the settling chamber and drop into the collecting chamber ll from which they are taken from the separator. Dust particles that may be retained in the gas and move along with the. gas flow can, be trapped by the filter screen [6 or a commercial air filter.

In the operation of the notation separator described above, a high velocity is required of the stream of material flowing over the porous partition 24, in order that, when the.- material comes into contact with the deflectors 35, the momenturn of the material will be such. that it will lift itself up and above the main material stream and deflect itself so as to allow the gas passing throughthe chamber to pass through this deflected material and carry off those particles that are light enough, in relation to the gas; velocity, to be car ried off. The coarse or heavier particles will fall back into the main material stream. Only a por tiorr the material. stream is deflected not all of the material stream is thus affected. If the entire streamwere deflected, the material, as it fell back onto the porous partition 2%, would have to start from zero velocity; and, by deflecting only a part of the stream, the undeflected partof the material stream. retains the velocity it has builtup thus allowing it to deflect itself at the next deflector with. as much energy as it de flected itself previously. It, would appear in this operation. that the gas flow and deflecting of a portion of the material stream are on an inter.-

'mittent basis, but this is not the case. The gas flow is constant and. the material flowis constant. The deflectors constantly split the material stream, part of the material stream continuing its original course and the deflected part of the material stream followinga constant path that is determined. by the position and relation of the deflectors 35 to the other parts of the separating chamber 23., The separating chamber side walls 25 and 49 taper inwardly as they ascend to the top thereof: forming a section that would be similar to an inverted v. By tapering the chamber 23, the gas velocity is increased as it passes therethrough, allowing a larger size material particle to be separated for a given quantity offiuidizing gas than if the walls were vertical.

The gas carries the fines through the inlet 22 into a settling chamber formed by the side wall of the casing l6 and the adjacent diverging baffie 20. The settling chamber is thus so shaped as to reduce the gas velocity allowing the fine particles of material to drop out of the gas stream into the collector IT. The baffle 26 directs all the gas downward and over the collector bin I? and thus increases the period of time within which the particles can drop out of the gas stream. The fine particles of material which gather in the collector bin I1 may be removed through the outlet [8 by opening the valve IS. The gas, after being reduced in velocity and dropping the fines passes upwardly through the diverging space between the bafiies 20 which serves as an exhaust stack and a further means of reducing gas velocity allowingthe extreme fines to drop out.

. The exhaust gas is filtered by the cloth H or otherwise treated to remove any solid material which remains therein.

The separating chamber 23 has been described hereinabove as an element of a fluid flotation separator tower. The separating chamber 23 may, however, be employed as a combined conveying and separating apparatus wherein separation is accomplished as the apparatus conveys a pulverized material from one point to another. Such a modified form of this invention is shown in Figures and 11. In this modification the separating chamber 23 may be from 50 to 100 feet in length or longer. The chamber is provided with a hopper 34) and a valve 3| at the inlet end thereof and a discharge spout 33 and a valve 34 at the outlet end thereof for controlling the admission and withdrawal of material to the chamber 23 without loss of the gas flowing in the chamber. The separating chamber 23 is similar in structure to that described above and includes a porous partition 24 which separates the plenum chamber 26 and separating chamber formed by the inclined side walls 25 and 40 and the top wall 31. The pulverized material agitating and elevating deflectors 35 are mounted within the chamber as previously described and are supported by the side walls 25 and 40. The inner side wall 40 is provided with a narrow elongated slot 22 near the top of the wall to provide an opening through which the gas having fines entrained therein may pass. A collecting chamber 6| is secured to the separating chamber or chute 23. The bottom of the chamber 6| has a screw conveyor 62 mounted therein. A vent 63 is provided in the top of the collecting chamber 6| adjacent thelower end thereof and a discharge spout 64 is provided in the bottom of the chamber 6| at the lower end thereof adjacent the end of the screw conveyor 62. The manner and theory of the operation of this modified form of the invention is the same as that of the fluid flotation separator described hereinabove. In this modified form of the invention the gas having fine particles of material entrained therein passes through the opening 22 into the collecting chamber 6|. The fines drop out of the gas and settle at the bottom of the collector where the screw conveyor 62 is located. The latter conveys the fines to the lower end of the collector chamber 6| and this material is then discharged through the spout 64. The gas which'has been relieved of the entrained fines passes through the vent 63 where, after it is filtered through a cloth or otherwise treated to remove all solid materials, it is released to the atmosphere.

A further modification of the form of the invention shown in Figures 10 and 11 is shown in Figure 12. The modified form of the invention disclosed in Figure 12 includes a separating chamber 23 having a collecting chamber 6| attached thereto. The bottom of collector BI is provided with a porous partition 24a below which is positioned a plenum chamber 26a and to which gas under pressure is supplied by a pipe 28a. The rate of flow of the gas fed to plenum chamber 26a is only enough to convey material. In this form of the invention the fine particles of material settle out of the gas entering the collector 6| through the opening 22 and fall upon the porous partition 24a. These fines are thereupon conveyed over the porous partition 24a to the lower end of the collector 6| and are discharged through the spout 64. The gas which is freed of the entrained fines passes through vent 63 in the manner described above. In this modified form of the invention the porous partition 24a may be a separate element or an integral part of the porous partition 24 as is shown in Figure 12. The plenum chamber 26a likewise may be a separate element or formed as an integral part of the plenum chamber 26 as is also shown in Figure 12.

An experimental form of a separating chamber is shown in an enlarged cross sectional View in Figure 13. The separator consists of an outer wall 25, a top 3'! and an inner wall 46, the latter being provided with a slot near the top thereof to provide the opening 22. The chamber is ten feet in length, 9.5 inches in height and 6.5 inches in width. The distance between the side walls 25 and 40 is 2.75 inches and the collecting chamber 6| attached to the separator chamber is 6 inches in depth measured downwardly from the lower edge of the opening 22. The venting of gas and the discharging of the fine particles of material is accomplished with a single outlet l6. At the bottom of the separator chamber there is a porous partition 22 which is formed of three-ply, untreated cotton transmission belting that is one-eighth inch thick. A plenum chamber 26 is positioned below the porous support 24 and is provided with a gas inlet line Three deflectors 35 are mounted in the separator chamber above the porous partition 26, which deflectors are formed of Wire screening having one half inch openings in the mesh thereof. 7

The porous partition 24 is capableof passing 3.5 cu. ft./min./sq. it. at a pressure of '7 inches of water and cu. ft./min./sq. it. of air at a pressure of 10 inches of water. The curve for pressure against volume is substantially colinear for this type of porous material. The gas is supplied to the plenum chamber 26 by a motor-blower unit capable of producing an output of 60 cu. itjmin. of gas which in the plenum chamber 26 produces a pressure of 7 inches of water, indicating that the rate of flow of gas through the porous partition is 3.5 cu. ft./min./sq. ft.

One test conducted with Type 1 Portland ce' ment in a slightly moist condition and having a fineness of 3000 on a Blaine fineness meter or 1600 on a Wagner turbidimeter resulted in the separation of fine particles of this material having a fineness of 3600 on a Blaine fineness meter or about 1900 on a Wagner turbidimeter. In this test the material stream flowing over the belting 13 was: deflected without reducing; the speed of the material stream. If the number of deflectors is increased to six,.the speed. of the material stream is reduced and effective separation is not obtained. Likewise, if the size of the openings in the: mesh of the wire screen employed as deflectors is reduced to one-eighthv inch, the material does not flow through the openings and the separation is not accomplished; The foregoing results are: indicative of what may be accomplished with: the particular material described which is in. the condition specified. In the foregoing form at the invention. the side walls 25 and 4!! were not inclined. toward the center of the chamber to decrease the cross sectional. area. thereof and thereby increase the velocity of the: gas flowing in. the: separating chamber.

In the foregoing description. of this invention the: fiuidizing medium has been referred to as a gas; This is intended to include within the mean ing thereof, in addition to air, inert gases such as nitrogen, carbon dioxide or the like that must bausedinseparating materials which, in a highly pulverized state may provide explosive mixtures. Itis also contemplated in this invention. to utilize gases for treating the material being separated. For example, the fluidizing gas may contai n gaseous insecticides or fungicides when a material is separated which is susceptible of serving as a host to insects, fungi, etc. The fluidizi n'g gas may contain oxidizing or reducing components in gaseous form when it is desirable to treat the material being separated therewith; such as, for example, a finely divided catalyst, or are particles.

I claim:

I. A. fluid separator comprising an elongated porous surface; means for supporting said surface at an angle to the horizontal to provide said surface with upper and lower ends; a chamber enclbsing the uppermost side of said porous surface and having inlet and outlet openings adjacent said upperand lower ends, respectively, said chamber having an outlet port for gas-borne particl'es near the top thereof; means for feeding a pulverized material to the uppermost end of said surface; means for passing gas under pressure through saidisurface from the lower side thereof to con-vey said pulverized material over said surface toward the" lowermost end thereof and to prowicie an upward flow of gas from the surface of the pulverized material conveyed over said porous. surface; a plurality of pulverized material; agitating and elevating deflectors; means for supporting said deflectors above said porous surface in an angular position inclined toward the outlet of said; chamber; each of said deflectors being spaced from adjacent deflectors lengthwise oi said elongated porous surface with the lowermost end of each deflector being spaced in the direction of the lower'end of said porous surface from the uppermost end. of the. adjacent deflector positioned nearest the upper end of said porous surface, and each of said deflectors being spaced above. said porous surface a. distance such that the lowermost end of each deflector extends below the surface of the pulverized material to a point relatively close to the surface of said pulverized material, the uppermost end of each defiector being spaced above the surface of the material on said porous surface and spaced from the inner top surface of said chamber to provide a passageway therebetween for pulverized material elevated by each of said deflectors, where- .ky' pulverized. material conveyed over said t4 porous surface is agitated, elevated above the surface; of the conveyed material, andpermitted to fallv downwardly through the stream, of gas flowing upwardly from the surface of the con.- veyedmaterial to allow relatively fine particles of pulverized material to become entrained in said upwardly flowing gas stream and relatively coarse particles to-fall onto the surface of the conveyed material on said porous surface in the region between said spaced deflectors; and means for withdrawing relatively coarser pulverized material adjacent the lowermost end, of said inclined porous surface.

2. A. fluid separator as set forth. in claim 1 characterized. that said. pulverized material agitating and elevating deflectors each comprises a relatively narrow elongated member.

3. A fluid separator; as set forth in. claim. 1 including means for controlling the.- rate of flow of. the gaspassed through said porous surface and. upwardly from the surface of the pulverized material conveyed thereover whereby the degree of fineness of the particles of pulverized mate,- rial entrained in. said upwardly flowing gas may be controlled.

4. A fluid. separator comprising a separator chamber having a material inlet opening in one endthereof and. a material out-let opening in the opposite end thereof, an elongated. porous partition positioned. in said chamber above the bottom wall of saidcharnber at. an angle to thehorizontal with the upper end thereof adjacent said material. inlet opening and. the lower end thereof adjacent said material outlet opening, means to supply gas under pressure into said chamber below said partition, means to supply material to be separated to the raised end of said partition whereby the, lighter particles of said material may be elevated to a position in said chamber above said partition and urged upwardly in the direction of gasilow through said partition, an outlet port for gasborne material positioned near the top of said chamber, the degree of slope of said partition and bouyant action of the gas flow being effective to cause the material to flow downwardly over; said porous partition at an appreciable velocity, and a series of pulverized materialeievating deflectors each including a relatively narcw elongated member positioned above said partition at a level to be contacted by material moving only relatively close to the upper surface of said moving material, each of said deflectors being spaced from adjacent deflectors [lenfihwise of said elongated porous partition with; the lowermost end of. each defiector'being spaced in the direction of the lower end of said porous partition from uppermost end of the adjacent deflector positioned nearest the raised end of said porous partition, and each of said deflectors. being disposed inan angular position inclined toward the outlet end. of said chamber, the uppermost end of each deflector being spaced above and overhanging the surface of material flowing on said partition and being spaced from the inner top surface of said chamber to permit said deflector members to agitate and elevate above the surfaceof the material flowing downwardly over said porous partition portions of the materiai adjacent said upper surface Without appreciably reducing the speed of said moving material. V

5. In a classifier separator of the type wherein the fines only of the material being separated are floated upwardly by the pressure and buoy- 'located above said partition, each of said deflector elements being spaced from adjacent deflector elements lengthwise of said elongated par tition with the lowermost end of each deflector element being spaced in the direction of the lower end of said partition from the uppermost end of the adjacent deflector element nearest the upper end of said partition, each element including a relatively narrow elongated member disposed in an angular position inclined toward the lowermost end of said partition, the uppermost end of each deflector element being spaced above and overhanging the surface of material flowing on' said partition and being spaced from the inner top surface of said chute chamber to provide a passageway therebetween for elevated material, each of said deflector elements extending through the surface of the material flowing on said partition and having the lowermost end thereof spaced above said partition to engage a small portion of material adjacent the upper surface of the material stream in a manner first to elevate said portion and thereafter release said portion to cascade said portion downwardly through said upwardly moving gas stream and expedite flotation of material fines.

6. In a classifier separator as set forth in claim 5 wherein the deflector elements consist of reticulated material having large openings in the mesh thereof through which the material stream may flow without reduction of the speed thereof.

'7. In a classifier separator as set forth in claim 5 wherein each of said deflector elements includes a plurality of narrow elongated members, each of which members consists of a narrow elongated flat strip of relatively rigid material and said separator chute chamber includes means positioned above said partition for supporting said strips.

8. In a classifier separator as set forth in claim 5 wherein the deflector elements consist of narrow elongated arcuate elements having a concave face and a convex face positioned in said chute chamber with the concave face of each of said elements facing the upper end of said partition whereby to permit said small portions of material engaged thereby to slide along said elements upwardly and thereafter to be released into said upwardly moving gas stream.

9. In a classifier separator as set forth in claim 5 wherein the deflector elements each consist of an arcuate portion of reticulated material having large openings in the mesh thereof through which the material stream may flow without reduction of the speed thereof, each of said arcuate portions of reticulated material having a concave face positioned adjacent the upper end of said partition.

10. In a classifier separator as set forth in claim 5 wherein the deflector elements each consists of a triangular plate having a base portion secured to the inner face of a sidewall of said chamber and the apex thereof overlying said partition, each of said triangular plates being arcuate and having a convex face and a concave face, each of said triangular plates being positioned in said chute chamber with the convex 16 face thereof facing the upper end of said parti tion.

11. A pneumatic separator comprising a relatively narrow elongated separator chute set at an angle to the horizontal, said chute having an elongated transverse partition of porous material set at an angle to the horizontal and serving as a support for pulverized material, said partition being adapted to pass gas under pressure, said chute being formed as a chamber below the partition, means to supply gas under pressure to said chamber, said chute having opposed side walls along the extent thereof forming a chamber above said partition, said walls being inclined tow rds each other adjacent the upper edges thereof, a plurality of deflector elements including relatively narrow elongated members mounted between said side walls, each of said deflector elements being spaced from adjacent deflector elements lengthwise of said elongated partition with the lowermost end of each deflector element being spaced in the direction of the lower end of said partition from the uppermost end of the adjacent deflector element nearest the upper end of said partition, said elements being positioned at an angle to the horizontal and being inclined towards the lower end of said chute, the uppermost edges of said deflector elements being spaced above the surface of the material on said artition and spaced from the inner top surface of the chamber above said partition to provide passageways between said elements and said surface of said chamber, the lowermost edges of said deflector elements being spaced slightly above said porous partition and positioned below the surface of the pulverized material on said partition, and a gas outlet port in one side wall approximately coextensive with the chute length whereby the velocity of gas supplied upwardly through the porous partition will be increased adjacent said outlet port to facilitate the entrainment into said gas of material deflected by said deflector elements.

12. A pneumatic separator as set forth in claim 11 wherein a collection chamber is attached to said separator chute, said collection chamber having an inlet port coextensive of and arranged in alignment with the outlet port provided in a side wall of separator chute, a bafiie positioned in said collection chamber adjacent said inlet port, said baffle extending downwardly from said inlet port and divergently therefrom whereby the velocity of the gas having material fines entrained therein is reduced as it flows downwardly over said baffle to permit said material fines to settle from said flowing gas, means for collecting said fines and means for conveying said gas to the atmosphere.

13. A pneumatic separator as set forth in claim 11 wherein a collection chamber is attached to said separator chute, said collection chamber having an inlet port coextensive of and arranged in alignment with the outlet port provided in a side wall of said separator chute, gas vent means in said collection chamber adjacent the top thereof, a material fines discharge means in said collection chamber adjacent the bottom thereof and conveyor means in said collection chamber for delivering material fines collected in said collection chamber to said material fines discharge means.

1%. A pneumatic separator comprising a vertically extending casing, a series of relatively narrow elongated separator chambers arranged serially in zig-zag relationinvertical tiers -on-adeflector element being spaced above the surface adjacent partition. and" of thematerial on the spaced from the adjacent inner tpp surface of said chamber to rovide a passageway therebetween forelevatedmaterial;the lowermost end of eaeh deflector element being spaced above the adiafient partition and positioned to extend into only the upper portion ofthe surface of the material flowing on said partition, each of said deflector elements in said chambers being spaced from adjacent deflector elements lengthwise of said elongated partition with the lowermost end of each deflector element being spaced in the direction of the lower end of said partition from the uppermost end of the adjacent deflector element nearest the upper end of said artition, the casing wall having an inlet point adjacent each chamber to permit gas to enter within the casing, a continuous downwardly extending baffie wall spaced inwardly from the inlet ports and diverging therefrom to direct the gas flow downwardly at reduced velocity, the upper end of the separator chamber having a gas outlet to permit escape of gas after it has passed downwardly to the lower end of the baffle, thence upwardly to said outlet, the lower end of the casing being closed to form a material fines collecting bin.

15. A separator as set forth in claim 14 wherein a pair of opposite side walls are provided with a similar series of vertical tiers of separator chambers and an opposed pair of downwardly extending baflie walls cooperating to form a common vertical gas return leading to the gas outlet. 16. A separator as set forth in claim 14 wherein the side walls of each separator chamber above each porous partition are set at an angle inwardly whereby to reduce the chamber cross-section and cause an increased gas-flow speed to ensure more efficient entrainment by the gas of the separated material fines.

17. A method for separating material fines from pulverized material comprising conveying a stream of ulverized material along an inclined porous surface, passing gas under pressure upwardly through said moving material stream, elevating a small portion of material from the uppermost region of said material stream adjacent the surface thereof to a point above said surface, releasing said elevated portion of material and allowing said portion to fall in the path of the gas flowing upwardly from the surface of said moving stream of material to entrain material fines in said gas and return coarse pulverized material to said flowing material stream, conducting said gas having material fines entrained therein to a point remote from said moving stream of material, and removing the material fines entrained in said gas.

18. A method as set forth in claim 17 which includes the step of reducing the velocity of the gas in conducting said gas having material fines entrained. therein to. a. oint remote. from v said moving material: stream.

19. A fluid separator comprising a. separator chamberhavinga material inlet openingin one opposite end thereof, an elongated porous partition positioned in said chamber above. the bottom wall of said. chamber at an angle to the horizontal. with. thefupper end thereof adjacent said material inlet opening and the lower end thereof adjacent said material. outlet opening, means to supply gas underpressure intosaid chamber below; said partition, means to supply material to be separated to the raised end. of said partition whereby thelighterparticles of said material may be elevated to a position in said chamber above.

said partition and-urged. upwardly in the direction of gas flow through said partition, anoutlet port for gas-borne materialppsitioned near the top of said chamber, the degree of slope of said parti and buorantaction. o the easnow being effective to cause the material to flow downwardly overpaid porous partition at an appreciable velocity, anda series of pulverized material elevating deflectors each including a relatively narrow elongated member positioned above said partition at a level to be contacted by material moving only relatively close to the upper surface of said moving material, each of said elongated members having a width substantially less than the width of said porous partition, each of said deflectors being spaced from adjacent deflectors lengthwise of said elongated porous partition with the lowermost end of each deflector being spaced in the direction of the lower end of said porous partition from the uppermost end of the adjacent deflector positioned nearest the raised end of said porous partition, and each of said deflectors being disposed in an angular position inclined toward the outlet end of said chamber, the uppermost end of each deflector being spaced above and overhanging the surface of the material flowing on said partition and being spaced from the inner top surface of said chamber to permit said deflector members to agitate and elevate above the surface of the material flowing downwardly over said porous partition portions of the material adjacent said upper surface without appreciably reducing the speed of said moving material.

20. In a fluid separator as set forth in claim 19 wherein the deflector elements each consists of reticulated material having large openings in the mesh thereof through which the material stream may flow without reduction of the speed thereof.

21. In a classifier separator of the type wherein the fines only of the material being separated are floated upwardly by the pressure and buoyancy of a moving gas stream, a separator chute chamber having a gas previous transverse elongated partition and an outlet for gas-borne material near the top thereof, said partition being set at an angle to the horizontal whereby material supplied to the upper end of said partition will flow therealong at an appreciable speed, a series of material elevating deflector elements located above said partition, each of said deflector elements being spaced from adjacent deflector elements lengthwise of said elongated partition with the lowermost end of each deflector element being spaced in the direction of the lower end of said partition from the uppermost end of the adjacent deflector element nearest the upper end of said partition, each deflector element including a relatively narrow elongated member having a Width substantially les than the width of said 19 partition and being disposed in an angular position inclined toward the lowermost end of said partition, the uppermost end of each deflector element being spaced above and overhanging the surface of material flowing on said partition and being spaced from the inner top surface of said chute chamber to provide a assageway therebetween for elevated material, each of said deflector elements extending through the surface of the material flowing on said partition and having the lowermost end thereof spaced above said partition to engage a small portion of material adjacent the upper surface of the material stream in a manner first to elevate said portion and thereafter release said portion to cascade said portion downwardly through said upwardly moving gas stream and expedite flotation of material fines.

Name Date Number Stebbins Oct. 14, 1902 Number 717,301 775,945 881,526 923,455

Number 20 Name Date Telford Dec. 30, 1902 Stebbins Nov. 29, 1904 Yount Mar. 10, 1908 Stebbins June 1, 1909 Payne July 22, 1913 Stebbins Aug. 19, 1924 Stebbins Dec. 2, 1924 Stebbins Oct. 11, 1927 Chance Oct. 1, 1929 I-Iaworth Jan. 28, 1936 Couveng Feb. 10, 1942 Frarer Mar. 10, 1942 FOREIGN PATENTS Country Date Netherlands Dec. 15, 1936 France Sept. 11, 1936 (4th addition to No. 673,694) Germany Oct. 3, 1889 Germany Oct. 26, 1939 Germany June 20, 1940 France Sept. 11, 1944 

